Lecture 34: Photosynthesis-light reactions Flashcards Preview

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Flashcards in Lecture 34: Photosynthesis-light reactions Deck (10)
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1

what initiates light reactions in photosynthesis?

absorbance of light

2

consequence of electron transfer reactions in light reactions?

1) production of QH2 or NADPH (NADH)
2)translocate H+ and generate a proton gradient across a membrane-used for ATP synthesis
3)in cyanobacteria and plants, O2 is produced from H20

3

why is it called Dark reactions

don't require light

4

Subsequent to the light reactions.... dark reactions...

-biosynthesis that uses the ATP and NADPH to fix CO2 as 3-phosphoglycerate
-3-phosphoglycerate is used then to make C4 to C7 sugars

5

What wavelength does visible light contain?

700nm (red) to 400 nm (dark blue)

6

Types of Photosystems

PS II
PS I
Complex PsI and PSII
PS1 + PSII

7

PS II

-in purple and green filamentous bacteria
-type II reaction center with P870 chlorophyll
-works with cytochrome bc1 complex in a cyclic system
-There is a H+ translocation but not net production of NADPH

8

PSI

-in green sulfur bacteria
-type 1 reaction center with P700 chlorophyll
-works either with cytochrome bc complex in a cyclic system without net production of NADPH
OR
with an electron done such as H2S or S2O32- with net production of NADPH

9

Complex PSI + PSII

in cyanobacteria
-photosystems act in series
-works with cytochrome bf complex
-organisms use H2O as source of electrons to reduce the primary pigment in PSII with a net production of NADPH

10

PSI+ PSII

in plants
-both systems act in series
-work with cytochrome bf
-H2O is used as source of electrons with net production of NADPH